Mixed grain photographic process



Feb. 7, 1950 w. T. HANSON, JR., ET A1. 2,496,940

MIXED GRAIN PHOTOGRAPHIC PROCESS Filed Oct. 21, 1948 2 Sheets-Sheet 1 UNSENSlT/ZED AyBr CULOR DEVELOPER CUNTA/N/NG MAGENTA AND YELLOW COUPLE/5' AND ANT/FOGGANT FIG.1.1

RED IMAGE Q) REMOVE UNDEVELOPED A 6? COLOR DEVELOPER CONMIN/NG' cmN REMOVE 31L V5)? m2 IMAGE COUPLER GREEN SENSITIVE A 6? YELLOW cwPLER RED SENSITIVE Agf'l cmN COUPLER F1614 UNSENSIT/ZED AgBr GREEN SENSITIVE A 1 YELLOW COUPLER j YELLOW FILTER RED SENSITIVE A 5r CYAN ('OUILER' RED SENSITIVEA (1 YELLOW you WESLEY T. HANSON, JR.

FORREST A. RICHEY INVENTORS GREEN JENSITIVZ'A c! (TY/MI COUPLER BY 7 TTORNEYS Fb. 7, 1950 r w. T. HANSON, JR, ET AL 2,496,940

MIXED GRAIN PHOTOGRAPHIC PROCESS Filed Oct. 21, 194s zsheets-sneet 2 AO/D'SOLUBLE RES [5 7' EED-SENSlT/ZEP A 6? COLOR DEVELOPER CONTAIN/N6 YELLOW COUPLER FIG. 2. 17- \L YELLOW or:

CD F/x Q) REMOVE RES/5T 1",? 24 Q) cow/e DEVELOPER comm/ ma MAGENTA comm AND ANT/FOGGA/VT YELLOW DYE REMOVE UNDEVELOPt'D A 62 MAGENTA DYE COLOR DEVELOPER CONMlN/N' cm C'OUPLER cm! DYE Z4 REMOVE s/LvL'R Z5 lllilllllllllllliililllfi WESLEY T. HANSON.JR FORREST A. RICHE g; YELLOW DYE INVENTORS WWW, BY H 7MZM ATTORNEYS Patented Feb. 7, 1950 MIXED GRAIN PHOTOGRAPHIC PROCESS Wesley T. Hanson, Jr., and Forrest A. Richey, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application October 21, 1948, Serial No. 55,686

4 Claims.

This invention relates to photography, and particularly to a mixed grain process of color photography.

Mixed grain processes of color photography have been suggested many times in photographic literature. One of the great difficulties with these processes is that of keeping the differently sensitized silver halide particles separate in the emulsion layer and processing them to obtain differently colored images. The present invention relates to processing the mixed grain emulsion layer to form the desired dye in the region of the separate silver halide grains.

It is known that silver chloride and silver bromide emulsions develop at different rates and it has frequently been reported that the differential rate of development of such emulsions can be made use of as a basis of a mixed grain color processs. The difierential rate of development of chloride and bromide emulsions is not sufficiently great, however, that the exposed grains can be separated upon development in this way, and mixed grain processes have not been made to operate successfully upon this principle.

It is, therefore, an object of the present invention to provide a novel mixed grain photographic process. A further object is to provide a method for differentiating between silver chloride and silver bromide grains upon development. Other objects will appear from the following description of our invention.

These objects are accomplished according to our invention by developing an exposed emulsion layer containing a mixture of silver bromide and silver chloride grains, with a primary aromatic amino developing agent containing one or more of certain compounds hitherto used as antifoggants. The antifoggants which we have found useful for the purpose of giving effective differential development of silver chloride and silver bromide emulsions are G-nitrobenzimidazole, 5-

nitroindazole, benzotriazole and 2-amino-5- methyl benzotriazole.

In the accompanying drawing are shown sectional views of films processed according to our invention.

The mixed grain emulsions used according to our invention are made by mixing an ordinary silver bromide or bromoiodide emulsion with a silver chloride emulsion which will ordinarily be sensitized to red or green light. In place of the silver chloride emulsion a chlorobromide emulsion may be used in certain cases, the distinction between si ver bromi e and silver chrobromide being made by the developers used according to our method.

The mixed grain emulsion may be used in conjunction with another emulsion either of silver bromide or silver chloride to form a threecolor process and the mixed grain emulsion may be coated on the same side of the support as the single emulsion either above or beneath it, or on the opposite side of the support. Either or both emulsion layers may contain a color coupler of the non-difi'using type or a coupler incorporated so as to reduce its diffusion tendency.

The developing agents used with the emulsion of our invention are primary aromatic amino developing agents such as diethylaminoaniline, 2- amino-5-diethylaminotoluene, N-ethyl-N-methylsulfonamidoethyl-p-phenylenediamine or 2,6- d i-iodo-&-aminophenol. These developing agents may be used in solutions containing soluble couplers in those cases where there is no coupler present in the emulsion layer.

In developing the mixed grain layers according to our invention, the exposed layer is first developed in a color developing solution suchjas that described above containing one or more of the antifoggants G-nitrobenzimidazole, 5-nitroindazole, benzotriazole and 2-amino-5methyl benzotriazole. These antifoggants are used in an amount of from 0.4 to 1 gram per liter of developing solution. Since this developing solution containing the antifoggant does not develop the exposed silver bromide to any appreciable extent, the exposed silver chloride only is developed. Any undeveloped silver chloride in the emulsion layer is then removed by fixing with a solution of sodium sulfite which removes the silver chloride but does not affect the silver bromide. The exposed silver bromide is then developed in anormal color developer, that is, a developer not containing the antifoggant. This developer may or may not contain a color coupler depending upon whether a coupler has been incorporated in the emulsion layer.

Example 1 A two-color mixed grain process may be carried out according to our invention as follows.

As shown in the first stage of Figure 1 of the drawing, a mixed emulsion layer of unsensitized silver bromide and green sensitized silver chloride emulsion ID was coated on a support II of any suitable material such as cellulose ester, synthetic resin or paper. The silver chloride grains of emulsion layer III were green sensitized 3 with a sensitizing dye having little or no tendency to wander, for example, -(2-ethyl-1 (2) -benzoxazolylidene)-ethylidene-3-n-primary hepty1 l-phenyl-z-thiohydantoin. After exposure of this emulsion through a filter having a blue portion 5 I2 and a green portion l3, it was treated in a prebath of 10.0 grams of 6-nitrobenzimidazole nitrate per liter of water for one minute and was then developed in a developer of the following composition: 10

Grams p-Diethylaminoaniline 3 Sodium sulfite 5 Sodium carbonate Potassium chloride 2 1-phenyl-3- (p-nitrobenzoylamino) B-pyrazolone 3 w-Benzoylacetanilide 0.6 Sodium hydroxide 1.3 G-nitrobenzimidazole-nitrate 10.5 20 Water to 1 liter.

After development for 14 minutes and washing for 4 minutes, the :film appeared as shown in the second stage of Figure l of the drawing with a red image 14 in the portion of the layer exposed to green light. The red image was formed by the mixture of magenta and yellow couplers in the developing solution.

The :film was then treated .for 4 minutes in a differential fixing bath .of 100 grams of sodium sulfite per liter of water to remove undeveloped silver chloride without afiecting the silver bromide. ,After a further 4 minute wash, the film was developed for eight minutes .in a second color 5 developer of the following composition:

Grams 2-amino-5-diethylaminotoluene 2 Sodium sulfite 5 Sodium carbonate 15 Potassium bromide 5 2,4-dichloro-l-naphthol 1.5 Sodium hydroxide 1.3 Water to 1 liter.

After a 10 minute wash and bleaching in the following solution:

Grams Potassiumrferricyanide "'80 Potassium bromide 20 Water to 11 liter.

and a further rinse and treatment in the following hypo solution to remove all silver and undeveloped silver halide: 5a

Grams Sodium sulfite 10 Sodium thiosulfate .200 Water to 1 liter. and a further 10 minute wash, the film appeared as shown in the last stage of Figure 10f the drawing with a red image l4 and a cyan image IS in the emulsion layer.

Example 2 A three-color mixed grain process using a film having emulsion layer coated on both sides of the support maybe carried out according to our invention as follows:

- As shown in the first stage of Fig. 2 ofthe drawing, a silver chloride emulsion l6 sensitized to red light 'with 13,3'--dimethy1-4,5,4';5-dibenzthiacarbocyamne iodide was coated on one side of asupport 1 l of any suitable transparent material such as cellulose ester, synthetic resin or paper. On the opposite side of support l1, there was coated a layer I8 of unsensitized silver bromide mixed with green-sensitized silver chloride, the emulsion layer [8 being similar to the emulsion layer In of the preceding example. Over emulsion layer 18 there was coated a layer IQ of an acid-soluble resist, for example, polyvinyl pyridine (French Patent 849,126).

After exposure of this film, through a filter having a blue portion 20, a green portion 2| and a red portion 22, it was developed for three minutes in a developer of the following composition:

Grams 2-amino-5-diethylamino toluene 3 Sodium sulfite 2 Sodium carbonate 20 Potassium chloride 4 Potassium bromide 1 Sodium hydroxide 2 o-Benzoylacetanilide 3 Water to 1 liter.

This development formed a yellow image 23 in emulsion layer I 6 as shown in the second stage of Fig. 2 of the drawing, without affecting the exposed grains of emulsion layer 1.8. The resist layer l9, being soluble only in acid solution, prevented penetration of the alkaline developer solution to the 'layer l8. The residual silver chloride was removed from the layer l6 and it was then fixed for two minutes in the following alkaline solution:

Grams Sodium sulfite 10 Sodium thiosulfate 200 Waterto 1 liter.

After washing in water for three minutes, the resist layer 19 was removed by treatment in the following solution:

Sodium sulfite grams 15 Acetic acid (28% solution) cc 47 Boric acid (crystals) grams 7.5 Potassium alum do 15 Water to 1 liter.

After again washing for three minutes, the film was treated for three minutes in a solution of 10 grams of B-nitrobehzimidazole nitrate per liter of water, rinsed and a magenta dye image formed in layer l8 by development for 4 minutes in the following developing solution:

Grams 2-amino-5-diethylamino toluene 4 Sodium sulfite 2 Sodium carbonate 20 Potassium chloride 2 S-nitrobenzimidazole nitrate 1 Sodium hydroxide 2 1-phenyl-3- (p-nitrobenzoylamino) -5 pyrazolone 4 Water to 1 liter.

This resulted in the formation of a magenta dye image 24 in the portions of emulsion layer 18 exposed to green light. Because of the presence of G-nitrobenzimidazole in the developing solution, only the silver chloride of layer l8 was developed and the silver bromide was not affected.

After washing for three minutes and treatment for 4 minutes in a difierential fixing bath of 100 grams of sodium sulfite per .liter of water to remove undeveloped silver chloride without afiecting the silver bromide in layer 18, the film was washed for 3 minutes and developed for 3 minutes in a cyan color developer of the following composition Water to 1 liter.

After washing in water for minutes, the

silver was bleached in the following solution:

Grams Potassium ferricyanide 80 Potassium bromide 20 Water to 1 liter.

and the film was rinsed and fixed in the following bath:

Grams Sodium sulfite 10 Sodium thiosulfate 200 Water to 1 liter.

Example 3 A three-color mixed grain process may be I carried out alternatively using the film shown in Fig. 3 of the drawing in which a support 26 of any suitable material such as cellulose ester, synthetic resin or paper, was coated with superposed emulsion layers 21 and 28. Emulsion layer 21 was a silver chloride emulsion sensitized to red light as described in the preceding example and containing 7.5 grams per liter of emulsion of the cyan-producing coupler, 4,6-dichloro-5- methyl 2 (2,4' di tert.amylphenoxyacet amino) phenol. Emulsion layer 28 consisted of a mixture of unsensitized silver bromide and green-sensitive silver chloride, the silver chloride grains being sensitized to green light as described in the preceding examples. Emulsion layer 28 also contained 7.5 grams per liter of emulsion of the yellow-forming coupler:

N-(4-benzoyl acetamino benzene sulfonyD-N- benzyl-m-toluidine. Both the cyan and yellow couplers were incorporated in the emulsion layers in the manner described in Jelley and Vittum U. S. Patent 2,322,027.

After exposure of the film described in Fig. 3 of the drawing, the film was treated for 1 minute in a pre-bath of B-nitrobenzimidazole nitrate, rinsed and developed for 14 minutes in the following solution:

Grams 2-amino-5-diethylamino toluene 3 Sodium sulfite 2 Sodium carbonate 20 fi-nitrobenzimidazole nitrate 0.5

Water to 1 liter.

This developer forms a cyan dye image in emulsion layer 21 and a yellow dye image in emulsion layer 28, only the exposed silver chloride grains being affected.

After treating the film for three minutes in a stop bath of the same composition as the resist 6 removal bath used in the preceding example and treatment in the differential fixing bath previously described, the film was then treated for 10 minutes in a developer of the following composition:

Grams 2,6-diiodo-4-amino phenol '7 Sodium sulfite 5 Sodium carbonate 20 Potassium bromide 2 Sodium hydroxide 2 1-phenyl-3- (p-nitrobenzoylamino) -5- pyrazolone 4 Water to 1 liter.

This developer formed a magenta dye image in the region of the exposed silver bromide grains in layer 28. The developer does not couple with either of the incorporated couplers in layers 21 and 28 so that no dye image is formed by this solution in the regions of the exposed silver chloride grains in these layers. The film was then washed and the silver removed by bleaching and fixing as described in the preceding example. This is a false color process since a yellow image is formed in the region of the green-sensitive grains and a magenta image in the region of the blue-sensitive grains in layer 28.

Example 4 A different type of two-layer, three-color material is shown in Fig. 4 of the drawing. As shown therein, the support 25 was coated with an emulsion layer 29, a yellow filter layer 30 and an emulsion layer BI. The emulsion layer 29 was red-sensitive silver bromide sensitized as described in the preceding examples and containing a cyan-forming coupler as described in the preceding example. Emulsion layer 3! consisted of a mixture of unsensitized silver bromide grains and green-sensitive silver chloride grains and contained a yellow-formin coupler. It was similar in all respects to emulsion layer 28 shown in Fig. 3.

After exposure, the material shown in Fig. 4 of the drawing was processed by first developing it in a solution of the following composition:

Grams 2,6-diiodo-4-amino phenol '7 Sodium sulfite 5 Sodium carbonate --20 Potassium bromide; 2 Benzotriazole 0.4 Sodium hydroxide 2 1-pheny1-3- (p-nitrobenzoylamino) -5- pyrazolone 4 Water to 1 liter.

Grams 2-amino-5-diethylamino toluene 3 Sodium sulfite 2 Sodium carbonate 20 Water to 1 liter. 

1. THE METHOD OF DEVELOPING A MULTI-COLOR IMAGE IN A PHOTOGRAPHIC EMULSION LAYER CONTAINING DIFFERENTLY-SENSITIZED SILVER BROMIDE AND SILVER CHLORIDE GRAINS, WHICH COMPRISES EXPOSING SAID EMULSION LAYER, DEVELOPING ONLY THE EXPOSED SILVER CHLORIDE GRAINS OF SAID LAYER WITH A COLOR DEVELOPER CONTAINING AN ANTIFOGGANT SELECTED FROM THE CLASS CONSISTING OF 6-NITROBENZIMIDAZOLE, 6 -NITROBENZIMIDAZOLE NITRATE, 5-NITROINDAZOLE, BENZOTRIAZOLE AND 2-AMINO-5-METHYL BENZOTRIA- 